Drug injection by syringe, pen injectors and other devices are used regularly for subcutaneous injections of therapeutic fluids, drugs, proteins, and other compounds. Such delivery systems and methods are used also routinely for insulin delivery. In conventional insulin injection pens, the pen is typically configured to include a disposable insulin reservoir and a disposable needle through which insulin is injected into the tissue. The needle is for single use, while the insulin reservoir can be used for two to three days.
In many instances, the patients require insulin injection around the clock to keep proper levels of glucose in their blood. Two major types of insulin can be injected—long-acting insulin that provides the basal insulin rate needed for keeping patient's blood glucose in the desired range between meals and over night and an insulin bolus injection that provides an amount of insulin for matching a dose of carbohydrates consumed by the patient during meals.
When a patient consumes food, his or her levels of glucose rise. Unfortunately, many conventional subcutaneous injection devices are incapable of quickly matching or preventing the rise of blood glucose. The delay in such matching is also true in case of the “rapid-acting” insulin. Some of the reasons for this delay include a lag in the absorption of insulin from the injection site and the time it takes for complex insulin molecules to break down into monomers.
Additionally, since blood glucose levels rise shortly following the meal, the delay in matching insulin to the rising levels causes post prandial hyperglycemic events (i.e., when levels of blood glucose are above normal) to occur. Further, occasionally after a certain period of time passes (e.g., 2-3 hours) after a meal, the blood glucose levels drop yet insulin concentrations in the blood rise followed by the peak of the systemic insulin effect and may result in causing hypoglycemic events (i.e., when levels of blood glucose are below normal) to occur. Both hyperglycemic and hypoglycemic events are highly undesirable. Additionally, since local blood perfusion at the insulin injection region has large variability, depending on the ambient temperature and other parameters, it induces large variations to the delay of the peak of time profile of the insulin action. Those variations in the insulin peak action period further increase the variability in the blood glucose level.
Therefore, it is desirable to provide a system and a method that provides efficient and rapid injection and absorption of a drug to the patient circulatory system. In particular, it is desirable to provide a system and a method for injection of insulin to the patient that improves effectiveness of insulin in the blood to maintain normal levels of blood glucose and prevent or reduce hyperglycemic and hypoglycemic events.